This invention relates to an air flow direction control valve and, more particularly, to a multi-way valve particularly adapted for use with an exhaust gas purifying system on an internal combustion engine to change the direction of flow of air to be mixed into exhaust gas for effecting additional combustion of the uncombusted constituents therein.
It is known that in order to purify exhaust gas from an internal combustion engine on an automobile and reform it into as harmless a gas as possible when it is discharged into the atmosphere, it is effective to introduce air into an exhaust gas purifying system and mix it with the exhaust gas from the engine to effect additional combustion of the exhaust gas and reduce the uncombusted constituents contained therein as much as possible. As is also known, it is necessary to change the direction of flow of the air in a complicated pattern to introduce the air into the purifying system through different portions thereof from time to time during the operation of the engine in order to obtain an optimum effect at any time, for example, when the speed of the automobile is reduced or when the exhaust gas purifying system is overheated. In order to meet this requirement, it has been customary to use a couple of three-way valves either separately or in a combined unit. The device is, however, complicated in construction and requires a considerably large space for installation. The device is expensive and a great deal of time, labor and materials are required to install it in an exhaust gas purifying system. Moreover, a complicated mechanism is required to operate such a complicated device to change the direction of flow of air as required.